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* Copyright (c) 2012 Luca Barbato
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* This file is part of FFmpeg.
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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* url syntax: sctp://host:port[?option=val...]
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* option: 'listen' : listen for an incoming connection
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* 'max_streams=n' : set the maximum number of streams
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* 'reuse=1' : enable reusing the socket [TBD]
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* by setting the maximum number of streams the protocol will use the
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* first two bytes of the incoming/outgoing buffer to store the
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* stream number of the packet being read/written.
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#include <netinet/in.h>
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#include <netinet/sctp.h>
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#include "libavutil/intreadwrite.h"
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#include "libavutil/parseutils.h"
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#include "libavutil/opt.h"
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#include "os_support.h"
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* The sctp_recvmsg and sctp_sendmsg functions are part of the user
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* library that offers support for the SCTP kernel Implementation.
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* To avoid build-time clashes the functions sport an ff_-prefix here.
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* The main purpose of this code is to provide the SCTP Socket API
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* mappings for user applications to interface with SCTP in the kernel.
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* This implementation is based on the Socket API Extensions for SCTP
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* defined in <draft-ietf-tsvwg-sctpsocket-10.txt>
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* Copyright (c) 2003 International Business Machines, Corp.
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* Written or modified by:
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* Ryan Layer <rmlayer@us.ibm.com>
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static int ff_sctp_recvmsg(int s, void *msg, size_t len, struct sockaddr *from,
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socklen_t *fromlen, struct sctp_sndrcvinfo *sinfo,
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char incmsg[CMSG_SPACE(sizeof(struct sctp_sndrcvinfo))];
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struct msghdr inmsg = { 0 };
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struct cmsghdr *cmsg = NULL;
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inmsg.msg_name = from;
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inmsg.msg_namelen = fromlen ? *fromlen : 0;
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inmsg.msg_control = incmsg;
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inmsg.msg_controllen = sizeof(incmsg);
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if ((recvb = recvmsg(s, &inmsg, msg_flags ? *msg_flags : 0)) < 0)
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*fromlen = inmsg.msg_namelen;
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*msg_flags = inmsg.msg_flags;
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for (cmsg = CMSG_FIRSTHDR(&inmsg); cmsg;
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cmsg = CMSG_NXTHDR(&inmsg, cmsg)) {
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if ((IPPROTO_SCTP == cmsg->cmsg_level) &&
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(SCTP_SNDRCV == cmsg->cmsg_type))
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memcpy(sinfo, CMSG_DATA(cmsg), sizeof(struct sctp_sndrcvinfo));
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static int ff_sctp_send(int s, const void *msg, size_t len,
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const struct sctp_sndrcvinfo *sinfo, int flags)
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struct msghdr outmsg = { 0 };
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outmsg.msg_name = NULL;
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outmsg.msg_namelen = 0;
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outmsg.msg_iov = &iov;
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iov.iov_base = (void*)msg;
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outmsg.msg_iovlen = 1;
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outmsg.msg_controllen = 0;
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char outcmsg[CMSG_SPACE(sizeof(struct sctp_sndrcvinfo))];
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struct cmsghdr *cmsg;
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outmsg.msg_control = outcmsg;
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outmsg.msg_controllen = sizeof(outcmsg);
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outmsg.msg_flags = 0;
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cmsg = CMSG_FIRSTHDR(&outmsg);
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cmsg->cmsg_level = IPPROTO_SCTP;
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cmsg->cmsg_type = SCTP_SNDRCV;
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cmsg->cmsg_len = CMSG_LEN(sizeof(struct sctp_sndrcvinfo));
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outmsg.msg_controllen = cmsg->cmsg_len;
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memcpy(CMSG_DATA(cmsg), sinfo, sizeof(struct sctp_sndrcvinfo));
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return sendmsg(s, &outmsg, flags | MSG_NOSIGNAL);
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typedef struct SCTPContext {
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const AVClass *class;
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struct sockaddr_storage dest_addr;
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#define OFFSET(x) offsetof(SCTPContext, x)
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#define D AV_OPT_FLAG_DECODING_PARAM
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#define E AV_OPT_FLAG_ENCODING_PARAM
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static const AVOption options[] = {
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{ "listen", "Listen for incoming connections", OFFSET(listen), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, 1, .flags = D|E },
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{ "timeout", "Connection timeout (in milliseconds)", OFFSET(timeout), AV_OPT_TYPE_INT, { .i64 = 10000 }, INT_MIN, INT_MAX, .flags = D|E },
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{ "listen_timeout", "Bind timeout (in milliseconds)", OFFSET(listen_timeout), AV_OPT_TYPE_INT, { .i64 = -1 }, INT_MIN, INT_MAX, .flags = D|E },
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{ "max_streams", "Max stream to allocate", OFFSET(max_streams), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT16_MAX, .flags = D|E },
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static const AVClass sctp_class = {
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.class_name = "sctp",
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.item_name = av_default_item_name,
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.version = LIBAVUTIL_VERSION_INT,
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static int sctp_open(URLContext *h, const char *uri, int flags)
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struct addrinfo *ai, *cur_ai;
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struct addrinfo hints = { 0 };
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struct sctp_event_subscribe event = { 0 };
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struct sctp_initmsg initparams = { 0 };
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SCTPContext *s = h->priv_data;
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char hostname[1024], proto[1024], path[1024];
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av_url_split(proto, sizeof(proto), NULL, 0, hostname, sizeof(hostname),
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&port, path, sizeof(path), uri);
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if (strcmp(proto, "sctp"))
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return AVERROR(EINVAL);
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if (port <= 0 || port >= 65536) {
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av_log(s, AV_LOG_ERROR, "Port missing in uri\n");
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return AVERROR(EINVAL);
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p = strchr(uri, '?');
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if (av_find_info_tag(buf, sizeof(buf), "listen", p))
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if (av_find_info_tag(buf, sizeof(buf), "max_streams", p))
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s->max_streams = strtol(buf, NULL, 10);
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hints.ai_family = AF_UNSPEC;
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hints.ai_socktype = SOCK_STREAM;
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snprintf(portstr, sizeof(portstr), "%d", port);
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ret = getaddrinfo(hostname, portstr, &hints, &ai);
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av_log(h, AV_LOG_ERROR, "Failed to resolve hostname %s: %s\n",
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hostname, gai_strerror(ret));
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fd = ff_socket(cur_ai->ai_family, SOCK_STREAM, IPPROTO_SCTP);
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if ((fd = ff_listen_bind(fd, cur_ai->ai_addr, cur_ai->ai_addrlen,
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s->listen_timeout, h)) < 0) {
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if ((ret = ff_listen_connect(fd, cur_ai->ai_addr, cur_ai->ai_addrlen,
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s->timeout, h, !!cur_ai->ai_next)) < 0) {
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if (ret == AVERROR_EXIT)
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event.sctp_data_io_event = 1;
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/* TODO: Subscribe to more event types and handle them */
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if (setsockopt(fd, IPPROTO_SCTP, SCTP_EVENTS, &event,
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sizeof(event)) != 0) {
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av_log(h, AV_LOG_ERROR,
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"SCTP ERROR: Unable to subscribe to events\n");
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if (s->max_streams) {
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initparams.sinit_max_instreams = s->max_streams;
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initparams.sinit_num_ostreams = s->max_streams;
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if (setsockopt(fd, IPPROTO_SCTP, SCTP_INITMSG, &initparams,
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sizeof(initparams)) < 0) {
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av_log(h, AV_LOG_ERROR,
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"SCTP ERROR: Unable to initialize socket max streams %d\n",
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if (cur_ai->ai_next) {
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/* Retry with the next sockaddr */
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cur_ai = cur_ai->ai_next;
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static int sctp_wait_fd(int fd, int write)
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int ev = write ? POLLOUT : POLLIN;
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struct pollfd p = { .fd = fd, .events = ev, .revents = 0 };
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ret = poll(&p, 1, 100);
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return ret < 0 ? ff_neterrno() : p.revents & ev ? 0 : AVERROR(EAGAIN);
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static int sctp_read(URLContext *h, uint8_t *buf, int size)
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SCTPContext *s = h->priv_data;
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if (!(h->flags & AVIO_FLAG_NONBLOCK)) {
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ret = sctp_wait_fd(s->fd, 0);
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if (s->max_streams) {
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/*StreamId is introduced as a 2byte code into the stream*/
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struct sctp_sndrcvinfo info = { 0 };
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ret = ff_sctp_recvmsg(s->fd, buf + 2, size - 2, NULL, 0, &info, 0);
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AV_WB16(buf, info.sinfo_stream);
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ret = ret < 0 ? ret : ret + 2;
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ret = recv(s->fd, buf, size, 0);
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return ret < 0 ? ff_neterrno() : ret;
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static int sctp_write(URLContext *h, const uint8_t *buf, int size)
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SCTPContext *s = h->priv_data;
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if (!(h->flags & AVIO_FLAG_NONBLOCK)) {
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ret = sctp_wait_fd(s->fd, 1);
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if (s->max_streams) {
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/*StreamId is introduced as a 2byte code into the stream*/
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struct sctp_sndrcvinfo info = { 0 };
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info.sinfo_stream = AV_RB16(buf);
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if (info.sinfo_stream > s->max_streams) {
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av_log(h, AV_LOG_ERROR, "bad input data\n");
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ret = ff_sctp_send(s->fd, buf + 2, size - 2, &info, MSG_EOR);
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ret = send(s->fd, buf, size, MSG_NOSIGNAL);
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return ret < 0 ? ff_neterrno() : ret;
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static int sctp_close(URLContext *h)
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SCTPContext *s = h->priv_data;
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static int sctp_get_file_handle(URLContext *h)
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SCTPContext *s = h->priv_data;
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URLProtocol ff_sctp_protocol = {
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.url_open = sctp_open,
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.url_read = sctp_read,
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.url_write = sctp_write,
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.url_close = sctp_close,
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.url_get_file_handle = sctp_get_file_handle,
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.priv_data_size = sizeof(SCTPContext),
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.flags = URL_PROTOCOL_FLAG_NETWORK,
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.priv_data_class = &sctp_class,